1. Field of the Invention
The invention relates to a radial piston machine and, more particularly, a radial piston machine that efficiently minimizes flow losses.
2. Description of the Related Art
From DE 40 049 32 C2 a radial piston machine is known, wherein a cylinder block having a multiplicity of radially disposed cylinder spaces is rotatably mounted in a housing. In each cylinder space one piston is guided, the end portion of which protrudes from the cylinder block and is supported on a cam ring. This cam ring has a multiplicity of control cams effecting a radial displacement of the pistons concurrently with a rotation of the cylinder block. In the housing of the radial piston machine, supply and return passages for pressure medium are formed which may alternatingly be made to coincide with control recesses in the cylinder block with the aid of which the supply and discharge of pressure medium to and from the cylinder spaces may be controlled.
In the embodiment described in DE 40 049 32 C2, the control recesses in the cylinder and the opening cross-sections in the housing are realized with a circular cross-section. It is a drawback in a like solution that the connections with the cylinder spaces are controlled open or closed comparatively slowly on account of the circular control cross-sections, so that flow losses may occur.
This drawback is overcome by a solution disclosed in EP 0 263 218 B1 wherein the control cross-sections are formed to be not circular but approximately trapezoidal. The lateral surfaces of these trapezoidal cross-sections may be designed to be curving inward, or planar.
Although it is possible with such a solution to minimize flow losses upon controlling the connection with the cylinder spaces open or closed, considerable expense in terms of production technology is necessary in order to form the trapezoidal control recesses.